Network devices (such as routers and switches) are often used to forward traffic within a network and/or across networks. These network devices may employ software that occasionally needs updating to fix certain bugs and/or improve performance. For example, a network device may include and/or execute an operating system that manages certain hardware and/or software resources. In this example, the network device may receive a software upgrade that is intended to patch a newly discovered security vulnerability, improve the operating system's performance, and/or provide support for new software across multiple platforms running the same operating system.
Unfortunately, the execution of traditional software upgrades may force network devices to shut down and reboot, thereby resulting in a certain amount of downtime during which the network devices are unable to forward traffic. Such downtime may be an undesirable but necessary side effect of the traditional software upgrades.
However, in the event that the traffic being forwarded by the network devices is critical and/or highly important, such downtime may simply be unacceptable. In those situations, in-service software upgrades may enable the network devices to upgrade their operating systems without shutting down to reboot. As a result, the network devices may be able to continue facilitating traffic without much, if any, disruption during the in-service software upgrades.
Unfortunately to support traditional in-service software upgrades, network devices may need certain redundant hardware (such as redundant routing engines and/or redundant linecards). This redundant hardware may increase the manufacturing costs of the network devices. The instant disclosure, therefore, identifies and addresses a need for additional and improved systems and methods for performing in-service software upgrades on active network devices.